(1) Field of the Invention
The present invention relates to an organic electroluminescence (EL) display device, and more particularly to an organic EL display device suitable for expanding the pixel area to obtain enhanced luminance.
(2) Description of the Related Art
Flat panel type display devices already in practical use or under research for commercialization include liquid crystal displays (LCD), plasma display panels (PDP), field emission displays (FED) and organic EL displays (OLED). Of these display devices, organic EL displays are very promising display devices as typical thin, light-weight self light-emitting display devices. There are two different types of organic EL display devices, including the so-called bottom emission type and top emission type. The present invention is applied to organic EL display devices of the bottom emission type.
A bottom emission type organic EL display device is formed of multiple organic EL light emitting layers (organic EL elements), each of which emits light in a prescribed color, stacked over one (lower electrode) of transparent electrodes formed for each pixel over the inner face of a transparent substrate, such as a glass substrate, and the other electrode (upper electrode) formed over that lower electrode. By applying a voltage between the lower electrode and the upper electrode to inject holes and carriers into the organic EL light emitting layers, lights of prescribed frequencies (color lights) are emitted. By arranging a plurality of such pixels two-dimensionally (in a matrix), an image is displayed. Such a display device is disclosed in Japanese Patent Application Laid-Open Publication No. 2003-122301 for instance. Japanese Patent Application Laid-Open Publication No. 2003-122301 describes an organic EL display device which is provided with a capability to display satisfactory moving pictures by controlling the luminescence per frame of the image with display data.